Carburetor



H. H. TlMlAN CARBURETOR Filed Feb. 7. 1929 will] il Hamm,

Nov. 24, 1931.

Patented Nov. 24, 1931 UNITED STATES PATENT OFFICE HAROLD H. TIIIAN, 0FINDIANAPOLIS, INDIANA, ASSIGNOB TO THE WHEELER- SCHEBLER CABSBURETEBOOHPANY, A CORPORATION OF INDIANA.

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Application led Iebrunry 7, 1829. Serial No. 838,10. I

This invention relates to carburetors for internal combustion enginesadapted to be intermittently operated under supercharging pressures.

lVhen superchargers are fitted to internal combustion engines, thecarburetor system may be located either outside thel supercharger orbetween the supercharger and the engine cylinders. The present inventionrelates to the latter location of the carburetor, which presentsproblems in the variation of pressure in the carburetor when thesupercharger is yin operation, in the control of the mixture ratio dueto the variation in pressure, and in the control of leakage from thecarburetor when the pressure therein is above atmospheric. It isdesirable to be able to disconnect the supercharger and operate theengine under normal conditions of intake suction when the added powerresulting from supercharged conditions is not needed.

Under such conditions of supercharger use, it is necessary that themetering characteristics of a carburetor be materially enrichenedwhenever the motor is operated under the increased pressures produced bythe This enriching of the mixture is in addition to the normalprovisions for adjustment to provide for range and power requirements.When the carburetor is subjected to the supercharger ressure eachmovable element forms a possi le avenue of escape for explosive mixture.It is accordingly an object of this invention to inclose all theadjustable members, including the accessories attendant upon theflexibility of the carburetor, in a housin subjected to the superchargerpressure an to lead one or more control members through the housing,providing packing only for the necessary control members thuseliminating a majority of the possible leakage points from thecarburetor.

Other and further important objects of this invention will be apparentfrom the disclosures in the specification and accompanying drawings.

This invention (in a preferred forrm) is illustrated on the drawings andhereinafter more fully described.

On! the drawings: HFigurel is an elevation of acarburetor embodyingfeatures of this invention, partly broken away to show details thereof.

Figure 2 is a section on the line II--II of Figure 1.

Figure 3 is a section on the line III-Hl of Figure 2.

As shown on the drawings:

A carburetor body l0 is shown as including a float chamber 11, the mainair inlet bein indicated at l2, together with a mounting ange 13 forattachment to the manifold system, and a throttle valve 14 mounted on athrottle shaft 15 which is operated in the usual way by a lever 16.

The particular internal arrangement of the carburetor has no bearing onthe subject of the present invention, and the particular meteringcontrol mechanism has been shown in some detail principally to disclosea specific embodiment of this invention.

The structure shown comprises an enriching cam 17 mounted on one end ofthe throttle shaft and adapted to engage the end of an adjustable screw18 carried by an arm 19 pinned on a rocker shaft 20 by a screw 21 havingan extension engaging in an aperture 23 associated with a fuel needlevalve 24. The screw 21 is made with a variety of sizes of the extension22 to provide a factory ad justment for the initial needle valvesettingi hic The cam 17 has a projecting arm 25 w has a link 26connecting to a rod 27 carrying an accelerating pump 'chamber 29 theaccelerating pump beingthus directly operated by an opening movement ofthe throttle shaft. The accelerating pump draws fuel from the floatchamber 11 through a passage 30a into a port 30 past a light flap valve31 and discharges through a passage32 leading to a chamberv 33 about theshank of the needle valve 24, the tapered point of the valve restrictingan outlet port 34 openin into a passage 35 leading to the fuel nozz e.The uel path just-outlined is effective when the pum is inactive becausethe head of fuel in the oat chamber 4is suiiicient to lift the light avalve 31.

he rocker shaft 20 also carries a cam 36 adapted to engage an adjustablescrew 37 carried by a projection 38 on the throttle lever 16 to slightlyopen the throttle from its extreme closed position when a spring 39,connecting the cam 36 to a choke valve control 40, is tensioned byclosing of the choke valve when it is desired to start the engine.

The structure heretofore described forms the normal range and poweradjustments and the accessories provided to secure flexibility in anunsupercharged carburetor. In order to provide the required additionalfuel when the increased supercharger pressures are imposed on thecarburetor, the arm 19 is provided with a second adjustable screw 4lwhich is adapted to be engaged by a cam 42 carried by a stub shaft 43independent of but coaxial with the throttle shaft 16. This stub staftis provided with an operating lever 44 which is intended to be linked tothe supercharger control in such a manner that when the supercliarger isplaced in operation the cam 42 will be turned to engage its screw 4l torock the shaft 2O and thereby lift the needle valve to enrich themixture by allowing the passage of more fuel through the port 34.

When using the supercharger pressure in the carburetor the pressurebecomes above atmospheric and causes each journal to become' a possibleleakage point for the fuel and air mixture. In order to reduce thenumber of points where provision against leakage must be made, theenriching mechanism is enclosed in a sealed casing 45 having a vent hole46 opening into the float chamber, and having a tapped inlet 47 to thehousing which is intended to be connected to the supercharger, thus ineffect forming a jacket subjected to pressures at least equal to theibnormal pressures imposed on the carbure- Those connections which mustnecessarily be externally operatable are provided with packing membersadapted to increase the sealing surfaces. The packing comprisesexternally threaded sleeves 48 secured to the shafts and engaging inthreaded apertures in the'carburetor walls or casing walls. The sleevesrotate with the shafts and hence dis- -place the latter slightlyalthough the extent of longitudinal movement is slight due to the smallangle of movement and tine pitch of threads, so that the normalmanufacturing clearances are ample to permit the necessary movement,vwhile the threads surfaces materially increase the bearing area of theseal.

It will thus be seen that I have provided means for enriching themixture when the carburetor is operated under supercharging conditionsand have at the same time reduced the possibility of leakage from thecarburetor and balanced the pressure in the float chamber.

I am aware that numerous details of construction may be varied through awide range without departing from the principles of this invention, andl therefore do not purpose limiting the patent granted, otherwise thannecessitated by the prior art.

l claim as my invention:

l. A carburetor adapted for use with superchargers, comprising a fuelmetering system having enriching means for normal full power operation,independent means adapted to actuate said enriching means for use undersupercharged conditions, a housing enveloping said enriching means andhaving a pressure connection whereby to subject said means tosupercharger pressure,

said housing having a connection to the carburetor float chamber,outside operating members for said carburetor extending through thewalls of said housing, and movable threaded packing members engaging insaid housing about said operating members to increase the sealingsurface at said operating members.

2. A carburetor adapted for use with supercliargers, comprising a fuelmetering system having enriching means for normal full power operation,independent means adapted to actuate said enriching means for use undersupercharged conditions, a housing enveloping said enriching means andhaving a. pressure connection whereby to subject said means tosupercharger pressure, said housing having a connection to thecarburetor float chamber, outside operating members for said carburetorextending through the Walls of said housing, and packing membersvassocia-ted with said operating members having a threaded surfacerotatable against a similar threaded surface in the housing wall toprevent leakage at said outside operating members.

3. A carburetor adapted for use with superchargers, comprising a fuelmetering system including means for normally enriching the mixture forfull power operation "f under non-supercharged conditions, means forindependently actuating said enriching means whereby to provideadditional fuel for supercharged conditions, a housing enveloping saidenriching means, control members projecting through threaded openingstherefor in said housing and threaded surfaces associated with saidcontrol members and engaging in said threaded openings.

4. A carburetor adapted for use with supercliargers, comprising a fuelmetering system including means for normally enriching the mixture forfull power operation under non-supercharged conditions, means forindependently actuating said enriching means whereby to provideadditional fuel for supercharged conditions, a housing enveloping saidenriching means, a pressure connection to said housing whereby tosubject the interior thereof to supercharger pressure, control membersprojectin through threaded openings therefor in sai housing and threadedsurfaces associated with said control members and engaging in saidthreaded openings.

5. A carburetor adapted for use with an intermittently operatingsupercharger, comprising a fuel metering system, said fuel meteringsystem comprising means for enriching the normal or economy setting toprovide for full power operation under nonsupercharged conditions, andmeans providing an independent and more extended range of enrichment forsaid fuel metering system for supercharged conditions.

6. A carburetor adapted for use with an intermittently operatingsupercharger, comprising a fuel metering system, said fuel meteringsystem comprising means for en- ,20 riching the normal or economysetting to provide for full power operation under nonsuperchargedconditions,` means providing an independent and more extended range ofenrichment for said fuel metering system i* for supercharged conditions,a housing enveloping said enriching means, and a pressure connection tosaid housing whereby t0 subject the interior'thereof to the superchargerpressure when the latter is in oper- Sf" ation.

In testimony whereof I have hereunto subscribed my name at Indianapolis,Marion County, Indiana.

HAROLD H. TIMIAN.

